There are fewer PCBs in Spokane River fish than previously thought, according to results of a 1994 study.
Levels of the dangerous chemical compounds found in samples taken last year were only half as high as those found in a 1993 study, according to the Washington Department of Ecology.
Health officials still recommend, however, that people take precautions when they eat fish caught between Nine Mile Dam and the Idaho border.
Health warnings were posted along that stretch of the river after the 1993 study found unhealthy levels of PCBs, mostly in the Spokane Valley’s industrial corridor.
“In some cases, the levels found in our more extensive study are 50 percent lower, but they’re still higher than we want,” said Carl Nuechterlein, who oversaw both studies.
PCBs are suspected of causing cancer, and are known to cause birth defects, nerve disorders and other health problems. Although used in electrical transformers and various industrial processes, their manufacture was banned in the United States in 1977.
State health officials are analyzing the information collected in 1994. Meanwhile, the Spokane County Health Department is maintaining its earlier recommendations:
Because PCBs accumulate in fat, fish should be trimmed of all fat possible before cooking. They should be cooked on a rack to allow remaining fat to drain away.
People with doubts about the health effects of eating Spokane River fish should avoid them.
Exposure to the river water poses no threat to human health because the level of PCBs in the water is extremely low, said county health official David Swink.
Fish-eating birds and mammals are still at risk from PCBs, Nuechterlein said, because they eat large amounts of whole fish. Samples of whole fish from both studies show PCB levels six times higher than the amount thought to be safe for wildlife.
The lower levels of PCBs found in 1994 may be the result of several factors, said Nuechterlein.
Explanations could include: dropping concentrations of PCBs; a larger sample size in 1994 that could be more representative of actual concentrations; and the cleanup of industrial sources along the river.
Kaiser Aluminum’s Trentwood plant, for example, cleaned out a lagoon. The company also is purging PCB-contaminated sludge from an old sewer line, Nuechterlein said. Cooling water flows through that line, and that could be “bleeding” chemicals into the river.
The two studies cost more than $200,000. There is no money for additional sampling in 1995, Nuechterlein said. But Ecology made these recommendations for future action:
Take more samples at the Liberty Lake sewage treatment plant to confirm or quantify its importance as a possible source of PCBs in the river.
Collect more samples at the Spokane Industrial Park to determine its importance as a possible source of PCBs at the Spokane Wastewater Treatment plant. The industrial park no longer discharges into the river.
Re-analyze PCBs in the effluent from the Kaiser plant to confirm the presence of a specific type of PCB and to monitor cleanup of the cooling water line.
Review available information on potential sources of PCBs found in the Little Spokane River whitefish in 1994, and sample as needed.
Re-sample fish in the upper Spokane River in 1996 to find out if PCB contamination is actually dropping.